Studies on Plum pox (sharka) resistance in apricot

Abstract

The Mediterranean countries account for more than 50% of world apricot production. However, the spread of the Plum pox virus (PPV) in this area represents a limitation for this crop. In Spain, since 1987 the virus has been spread very fast on apricot, causing fruit deformations that resulted in important losses. A project based on eradication of infected foci did not stop the disease in Valencia. In 1993, an apricot breeding program was initiated at IVIA, based on crosses between North American cultivars resistant to PPV and native cultivars susceptible to the virus. An efficient procedure that allowed to determine the PPV resistance in the progenies was addressed. Using this procedure, eight different families from crosses, made from 1993 to 1996, between resistant and susceptible cultivars were screened. Seedlings from these crosses were classified according to the trait, resulting in a segregation of 3:1 susceptible/resistant to the PPV. This segregation adjusted to the hypothesis of two independent dominant loci. The donors of resistance used would be heterozygous for both loci. Only those seedlings heterozygous for both loci, as the parental donors, would be resistant. Among the seedlings that resulted resistant to PPV, three out of them were selected, because of its good fruit quality. They could be an alternative to the native cultivars susceptible to the virus. Two seedlings came from a cross between Goldrich and Ginesta and one came from a cross between Stark Early Orange and Palau.